Crystal phase evolution in kinked GaN nanowires

Abstract

Seed-catalysed growth has been proved to be an ideal method to selectively tune the crystal structure of III–V nanowires along its growth axis. However, few results on relevant nitride NWs have been reported. In this study, we demonstrate the growth of epitaxial kinked wurtzite (WZ)/zinc-blende (ZB) heterostructure GaN NW arrays under the oxygen rich condition using hydride vapour–liquid–solid vapour phase epitaxy (VLS-HVPE). The typical GaN crystal includes WZ and ZB phases throughout the whole NW structure. A detailed structural analysis indicates that a stacking faults free zone was occasionally observed near the NW tips and in the relatively long kinked 〈11-23〉 directions segments (>200 nm). Furthermore, some NWs (<5%) develop phase boundaries, resulting in kinking and crystal phase evolution. A layer-by-layer growth mode was proposed to explain the crystal phase evolution along the phase boundaries. This study provides new insights into the controlled growth of wurtzite (WZ)/zinc-blende (ZB) heterostructure GaN NW.